Abstract

This PhD thesis provides an extended evaluation of evolutionary debunking arguments in meta-ethics. Such arguments attempt to show that evolutionary theory, together with a commitment to robust moral objectivity, lead to moral scepticism: the implausible view that we lack moral knowledge or that our moral beliefs are never justified (e.g. Joyce 2006, Street 2005, Kahane 2011). To establish that, these arguments rely on certain epistemic principles. But most of the epistemic principles appealed to in the literature on evolutionary debunking arguments are imprecise, confused or simply implausible. My PhD aims to rectify that. Informed by debates in cutting-edge contemporary epistemology, Chapter 1 distinguishes three general, independently motivated principles that, combined with evolution, seem to render knowledge of robustly objective moral facts problematic. These epistemic principles state that (i.) our getting facts often right in a given domain requires explanation – and if we cannot provide one, our beliefs about that domain are unjustified; (ii.) higher-order evidence of error undermines justification; and (iii.) for our beliefs to be justified, our having them must be best explained by the facts they are about. Chapters 2-4 develop and critically assess evolutionary debunking arguments based on those principles, showing that only the one inspired by (iii.) succeeds. Chapter 2 investigates the argument that evolution makes explaining why we get moral facts often right impossible. I argue that Justin Clarke-Doane’s recent response (2014, 2015, 2016, 2017) works, yet neglects an issue about epistemic luck that spells trouble for robust moral objectivity. Chapter 3 discusses the argument that evolution provides higher-order evidence of error regarding belief in robustly objective moral facts. I show that such an argument falls prey to Katia Vavova’s (2014) self-defeat objection, even if evolutionary debunkers tweak their background view on the epistemic significance of higher-order evidence. Chapter 4 develops the argument that evolution, rather than robustly objective moral facts, best explains why we hold our moral beliefs. I offer a systematic, comprehensive defence of that argument against Andreas Mogensen’s (2015) charge of explanatory levels confusion, Terrence Cuneo’s (2007) companion in guilt strategy, and David Enoch’s (2012, 2016) appeal to deliberative indispensability. Chapter 5 brings everything together. It investigates whether robust moral objectivity survives the worry about epistemic luck raised in Chapter 2 and the explanatory challenge developed in Chapter 4. Making progress, however, requires a better idea of how we form true, justified beliefs about and acquire knowledge of robustly objective moral facts. Since it offers the most popular and best-developed epistemology of robustly objective morality, my inquiry in Chapter 5 focuses on contemporary moral intuitionism: the view that moral intuitions can be the source of basic moral knowledge. I argue that its success is mixed. While moral intuitionism has the conceptual tools to tackle the problem of epistemic luck from Chapter 2, it cannot insulate knowledge of robustly objective moral facts against the sceptical worry raised by the evolutionary debunking argument developed in Chapter 4. Thus, evolutionary theory, together with a commitment to robust moral objectivity, does lead to a form of unacceptable moral scepticism.